This application is based on Japanese Application No. 19619 filed on Jan. 28, 1999, Japanese Application No. 22324 filed on Jan. 29, 1999, and Japanese Application No. 23201 filed on Jan. 29, 1999, the contents of which are incorporated herein by reference.
This invention relates to a high current power source used primarily to power a drive motor for automobiles such as hybrid and electric automobiles.
A high current power source used to power an automobile drive motor achieves high output voltage by series connection of many battery cells. This is for the purpose of increasing drive motor output. A power source used for this type of application contains a large number of battery cells to increase output electrical power. For example, this type of power source is cited in Japanese Non-examined Patent Publication HEI 10-270006 (1998). As shown in the exploded oblique view of FIG. 1, the power source disclosed in this patent application is provided with a holder-case 135 to house power modules in a plurality of rows. The holder-case 135 is formed of plastic in a box-shape with an open rectangular top. The holder-case 135 has circular through-holes 135a in both end walls 135A for insertion of long, slender circular columns of power modules. Further, intermediate, walls 135B are provided parallel to the end walls 135A to retain power modules in a stable manner, and these intermediate walls 135B also have circular through-holes 135b. Power modules are inserted through the holes 135a in both, end walls 135A and through the holes 136b in the intermediate walls 135B to retain the power modules in fixed positions within the holder-case 135.
This type of holder-case can reliably retain a plurality of power modules inserted into the through-holes. However, this type of holder-case has the drawback that its manufacture is markedly troublesome and manufacturing cost is high. This is because through-holes are formed for power module insertion and retention in both end walls and intermediate walls. Formation of a holder-case provided with through-holes in both end walls and intermediate walls requires a mold with a complex configuration. This is because regions of end wall and intermediate wall through-hole formations cannot be easily ejected from the mold.
In addition, through-holes provided in both end walls and intermediate walls of this type of holder-case must be formed to accurately fit the outline of the power modules. If a through-hole is larger than a power module, the power module cannot be retained without gaps. If a through-hole is smaller than a power module, the power module cannot be inserted into the through-hole. Unfortunately, power modules cannot be fabricated with a highly precise outline. This is because a power module is made by fixing devices such as temperature sensors to circular cylindrical batteries and covering the assembly with heat-shrink tubing. There is some error in the outline shape of circular cylindrical batteries manufactured in quantity. Additional variation in the outside diameter of a power module results from fixture of devices such as temperature sensors to the surface of the circular cylindrical batteries and application of the heat-shrink tubing. Consequently, since power module outlines differ, even if end wall and intermediate wall through-holes are formed with precision, it is difficult to insert all power modules into through-holes without forming gaps, thereby compromising reliable retention.
It is necessary to form through-holes for retaining power modules of variable outside diameter to a size which allows insertion of the power module with the largest outside diameter. Therefore, when a power module of somewhat smaller outside diameter is inserted into a through-hole, a gap develops between the power module and the through-hole. This holder-case has the drawback that when gaps develop at end walls and intermediate walls, power modules cannot be retained in a stable manner without moving.
Still another problem is the extreme effort of inserting and setting power modules in a holder-case formed with through-holes equal in size to power module outside diameter. This, is because power modules cannot be smoothly inserted into small through-holes designed to tightly fit the power modules with no gaps. For this reason, it is extremely troublesome to assemble a power source unit by inserting numerous power modules into a holder case, and assembly cost become high. High assembly cost compounded with the high cost of holder-case manufacture have the drawback that total cost of the power source is exceptionally high.
Still further, since the holder-case shown in FIG. 1 is formed from plastic in a single piece, the number of power modules housed within the holder-case cannot be changed. To change the number of power modules, it is necessary to fabricate another special holder-case for that purpose. Using a holder-case of single-piece construction does not allow changing the number of power modules housed within the holder-case.
The present invention was developed to resolve these types of problems with prior art power sources. Thus it is a primary object of the present invention to provide a power source with a holder-case that can be efficiently and inexpensively manufactured in quantity, which can be simply, easily, and efficiently assembled, and which can reduce total cost. Another important object of the present invention is to provide a power source wherein power modules are installed In a holder-case without gaps, power modules are reliably retained in a holder-case, and the number of power modules housed within a holder-case of simple Structure can be changed.
The above and further objects and features of the invention will more fully be apparent from the following detailed description with accompanying drawings.
The power source of the present invention holds a plurality of power modules disposed in a parallel fashion within a holder-case. The holder-case is provided with cover-casings located on both sides and intermediate-casings between the cover-casings. Further, holder-ribs to retain power modules at fixed positions in a plurality of rows are established projecting from both sides of intermediate-casings and from inside surfaces of cover-casings. Both side cover-casings and an intermediate-casing are joined together to sandwich and retain a plurality of rows of power modules in fixed positions with the holder-ribs provided on the cover-casings and intermediate-casing.
This configuration of this power source has the characteristic that the holder-case can be efficiently and inexpensively manufactured in quantity, power source assembly is simple and easy, and total cost is reduced. The holder-case of this power source does not require making a holder-case mold of complex structure as in the prior art. Rather, the holder-case can be efficiently and inexpensively produced in quantity with molds of simple structure. Further, since holder-ribs on the cover-casings and intermediate-casings allow power modules to be lined up in fixed positions, assembly is extremely simple and can be performed in a short time. Therefore, both manufacturing cost and assembly cost can be reduced for the power source of the present invention, and it has the characteristic that total cost is markedly reduced.
Further, the cover-casings and intermediate-casing are joined together to sandwich, from both sides, power modules lined up in a plurality of rows to retain them in fixed positions. Therefore, in addition to extremely simple assembly, the power source described above has the characteristic that power modules can be installed and reliably retained within the holder-case without gaps.
Still further, the power source described above has the characteristic that the number of power modules housed using a holder-case of simple structure (few pieces of single-piece construction) can be changed. This is because the power source is configured with cover-casings on both sides and one or more intermediate-casing disposed between the cover-casings. A plurality of rows of power modules are sandwiched by, and held in fixed positions by joining together the cover-casings and intermediate-casings. The number of levels of power modules arranged in rows can be simply increased or decreased to change the number of power modules retained by changing the number of intermediate-casings. Consequently, there is no need to fabricate a special purpose holder-case to change the number of power modules retained, and this type of power source realizes the characteristic that the number of power modules retained can be changed in various ways, depending on the application, using a holder-case of simple structure (few pieces of single-piece construction).
In this type of holder-case, shock-absorbing gaskets are connected to some part or to the entire holder-ribs, and power modules are held between casings via the shock-absorbing gaskets.